Effect of finite temperature correlations on plasmon and coulomb drag in coupled quantum wells

Abstract

We calculate the temperature dependence of correlations in coupled quantum wells using an STLS formalism generalized to finite temperatures. We investigate the effects of the temperature dependence of the correlations on the acoustic and optical plasmon dispersion curves and on Coulomb drag. Correlations are known to depress the energies of the two plasmons, while finite temperatures tend to increase the energies. We find this can result in considerable cancellation between the two effects at finite temperatures. We find that at temperatures k B T< E F, the local fields do not change appreciably with temperature so that in calculating the temperature dependence of the Coulomb drag using the zero temperature local fields suffices. The pair correlation function within the layers is also found to be insensitive to temperatures for k B T< E F. For higher temperatures than this the pair correlation function for small separations starts to increase as the exchange-correlation hole shrinks.